US computer systems engineer | Katholieke Universiteit Leuven, The Hill School | Pottstown: April 9, 1980 - Leuven: July 3, 2011 | Len Sassaman - Leonard

Dutch philosopher and artist | Sandberg Institute, Eindhoven University of Technology | Veldhoven: April 9, 1974 - Rome: June 27, 1935 | Koert van Mensvoort

German mathematician | Institute for Advanced Study, Harvard University, Leibniz University Hannover | Hanover: April 9, 1970 - Madison: December 21, 2014

American author, philosopher and neuroscientist (born 1967) | The End of Faith, Letter to a Christian Nation, The Moral Landscape, Making Sense with Sam

German archaeologist, humanities scholar and art historian | Martin Warnke Medal (2015) | Ahlen: April 9, 1963 - March 17, 1855 | Lambert Wiesing | Ahlen

April 9, 1961 - Barcelona: June 6, 1996 | Claude Danthony | April 9, 1961 - Barcelona: June 6, 1996

American chemist (1959-) | MRS Medal Award (2002), Clarivate Citation Laureates (2008), Wolf Prize in Chemistry (2012), Feynman Prize in Nanotechnology (2001)

Azerbaijani urologist | April 9, 1958 - Baku: June 30, 1955 | Əlimərdan Bağışov (Əlimərdan Bagisov) | April 9, 1958 - Baku: June 30, 1955

German astrophysicist | Karl Schwarzschild Medal (2023) | University of Greifswald | Jena: April 9, 1956 - Nuenen: February 17, 2012 | Thomas Henning | Jena

Belarusian Soviet and Russian jurist | Vitebsk State Academy of Veterinary Medicine, Moscow State Law University | Šumilina: April 9, 1956 - Kingston

Russian mathematician | School No80, Saint Petersburg, Faculty of Applied Mathematics - Control Processes, St. Petersburg State University | April 9, 1954

Brazilian philosopher and theologian | Pontifical Catholic University of Rio de Janeiro, University of Strasbourg | Crato: April 9, 1953 - July 22, 2021

US experimental physicist | Fellow of the American Association for the Advancement of Science, Fellow of the American Physical Society, Fellow of the Optical

American philosopher | Honorary doctor of the University of Groningen | Homewood-Flossmoor High School, Harvard University, University of Illinois Urbana–Champaign

American aerospace engineer | University of Washington (1992), University of Washington (1984), University of Rochester | New York City: April 9, 1952 - Padua

German chemist and professor at ETH Zurich | Elze: April 9, 1949 - Atherton: December 30, 2009 | Reinhard Nesper | Elze: April 9, 1949 - Atherton: December 30, 2009

German philosopher | Niedertiefenbach: April 9, 1948 - Aix-les-Bains: April 26, 1957 | Theo Kobusch | Niedertiefenbach: April 9, 1948 - Aix-les-Bains: April 26, 1957

American mathematician (born 1948) | Fellow of the American Mathematical Society (2013), Deborah and Franklin Haimo Awards for Distinguished College or

Mexican politician | honorary doctor of the University of Madrid Complutense (2000) | Minatitlán: April 9, 1948 - Des Plaines: August 20, 2015 | Patricia

Russian scientist | Merited Scientist of the Russian Federation | The Faculty of Geography and Geoecology | Saint Petersburg: April 9, 1945 - February 11, 2024

scientist | VDNKh gold medal, VDNKh silver medal | Moscow State Academy of Public Utilities and Construction | Moscow: April 9, 1940 - Budapest: January 8, 2017

German physicist | Technische Universität Berlin, University of Hamburg | Hong Kong: April 9, 1939 - Mainz: July 16, 2021 | Jürgen Körner (Jurgen Korner)

Welsh mathematician working in probability theory (1938-) | Fellow of the Royal Society, Pólya Prize (1994) | University of Oxford, Gowerton School, Jesus College

Soviet and Russian literary scholar | Dmitry Likhachev Foundation Prize (2012), Merited worker of culture of the Russian Federation (2015), Government Prize in

American mathematician | Harvard University | Bowling Green: April 9, 1934 - Zamora: June 5, 1908 | Andrew Ogg | Bowling Green: April 9, 1934 - Zamora: June 5, 1908

Polish physicist | University of Warsaw | Stary Ratyniec: April 9, 1932 - Warsaw: November 17, 2007 | Wojciech Ratyński (Wojciech Ratynski) | Stary Ratyniec

Japanese mathematician | Asahi Prize (1967), Person of Cultural Merit (1975), Guggenheim Fellowship (1971), Knight of the Legion of Honour, Japan Academy Prize

American chemist (1930-2007) | King Faisal International Prize in Science (1990), American Chemical Society Award in Inorganic Chemistry (1962), Foreign Member

Polish chemist (1930–2021) | Medal of Merit for National Defence, Gold Cross "For Merits to the Polish Scouting Association", Cross "For Merits to the Polish

American musician, satirist, and mathematician (born 1928) | National Brotherhood Week | Loomis Chaffee School, Harvard College, Horace Mann School, Harvard University

Brazilian physicist (1923–1948) | University of São Paulo | São Paulo: April 9, 1923 - São Paulo: August 21, 1948 | Sonja Ashauer | São Paulo: April 9

American mathematician and aerospace engineer | Congressional Gold Medal (2019) | Phoenix High School, Phenix High School, Hampton University | Hampton: April

German and British mathematician and physicist (1911-1991) | University of Göttingen, University of Cambridge | Żagań: April 9, 1911 - Detroit: January 19, 1991

Spanish chemist | Ávila: April 9, 1908 - State of Mexico: January 1, 2011 | Adela Barnés González (Adela Barnes Gonzalez) | Ávila: April 9, 1908 - State of

April 9, 1908 - Toulouse: May 31, 1931 | Petra Barnés González (Petra Barnes Gonzalez) | April 9, 1908 - Toulouse: May 31, 1931

English Jesuit priest and philosopher (1907–1994) | Commander of the Order of the British Empire, Aquinas Medal (1977), Fellow of the British Academy | A

American biochemist (1903–1967) | Cameron Prize of the University of Edinburgh, AMA Scientific Achievement Award (1967), National Inventors Hall of Fame

Belarusian poet, philosopher and publicist (1896-1923) | Vilna Realschule, Saint Petersburg State Institute of Technology, Imperial Moscow University

mathematician | University of Vienna, University of Toronto | Jasło: April 9, 1894 - Ontario: August 17, 1974 | Cecilia Krieger - Cypra Cecilia Krieger

German-American mathematician | Iron Cross (1918) | Frederick William University Berlin | Charlottenburg: April 9, 1894 - Chapel Hill: December 23, 1985

Spanish mathematician | Instituto de Coimbra (1947), Knight Commander of the Order of Alfonso X | Universidad Central | Haro: April 9, 1890 - Madrid: March 13, 1948

Spanish botanist (1888-1964) | honorary doctorate of the University of Montpellier (1959) | Introducció a l'estudi dels macromicets de Catalunya | Universidad

Japanese scientist | Kyoto University | April 9, 1885 - November 20, 1961 | Shōzō Toda (Shozo Toda) | April 9, 1885 - November 20, 1961

Russian political philosopher (1883–1954) | Moscow State University | Moscow: April 9, 1883 - Zollikon: December 21, 1954 | Ivan Ilyin | Moscow: April 9

mathematician (1878-1936) | University of Zurich, Berzsenyi Dániel Secondary School, ETH Zurich | Budapest: April 9, 1878 - Zurich: September 7, 1936 | Marcel

Swedish engineer (1877–1957) | Royal Institute of Technology | April 9, 1877 - Nacka församling: December 20, 1957 | Jonas Hesselman | April 9, 1877 - Nacka

Hungarian philosopher (1876-1933) | Budapest: April 9, 1876 - Budapest: June 29, 1933 | Ákos Pauler (Akos Pauler) | Budapest: April 9, 1876 - Budapest: June 29, 1933

academic administrator | Cornell University College of Agriculture and Life Sciences, Cornell University | Evansville: April 9, 1873 - Washington, D.C.

French mathematician (1869–1951) | Commander of the Legion of Honour, Foreign Member of the Royal Society (1947), Poncelet Prize (1920), Leconte Prize

German mathematician (1868–1950) | University of Göttingen | Hildesheim: April 9, 1868 - Gladbeck: January 1, 1950 | Friedrich Schilling | Hildesheim: April

chemist, businessman, I. G. Farben director and art collector (1867-1940) | Essen: April 9, 1867 - Frankfurt: November 20, 1940 | Carl Hagemann | Essen: April

mathematician, electrical engineer (*1865 – †1923) | National Inventors Hall of Fame (1977), Elliott Cresson Medal (1913), Cedergren Medal (1914)

British engineer (1864–1930) | Fellow of the Royal Society, Faraday Medal (1924) | University College London | Liverpool: April 9, 1864 - Zurich: January 13, 1930

Mathematics teacher (1863–1930) | Hungarian Heritage Award (2002) | Humboldt University of Berlin, University of Strasbourg, Eötvös Loránd University

Australian headmaster | University of Melbourne | Prahran: April 9, 1855 - Randwick: October 29, 1924 | John Marden | Prahran: April 9, 1855 - Randwick: October 29, 1924

Austrian photographer (1853-1927) | Wriezen: April 9, 1853 - Vienna: November 26, 1927 | Carl Pietzner | Wriezen: April 9, 1853 - Vienna: November 26, 1927

German chemist (1836-1918) | Hamburg: April 9, 1836 - Frankfurt: December 15, 1918 | Theodor Petersen | Hamburg: April 9, 1836 - Frankfurt: December 15, 1918

Baltic German physicist and music theorist (1836–1920) | Imperial University of Dorpat | Tartu: April 9, 1836 - Bensheim: September 5, 1920 | Arthur von

Colombian filologist, humanist and scientist (1834–1880) | Yale School of Medicine, University of Göttingen | Bogotá: April 9, 1834 - Beirut: July 28, 1880

mathematician from France | Poncelet Prize (1877) | École polytechnique | Bar-le-Duc: April 9, 1834 - Bar-le-Duc: August 14, 1886 | Edmond Laguerre

English-American photographer | National Inventors Hall of Fame (2011) | Sallie Gardner at a Gallop, Athlete Swinging a Pick | Kingston upon Thames: April 9

French astronomer (1816-1872) | Foreign Member of the Royal Society (1869), 72 names on the Eiffel Tower, Officer of the Legion of Honour, Gold Medal of the

French engineer (1815–1893) | Digne-les-Bains: April 9, 1815 - Vincennes: March 27, 1893 | Alphonse Beau de Rochas | Digne-les-Bains: April 9, 1815

Swedish politician (1814-1886) | Uppsala University | April 9, 1814 - Uppsala Cathedral Assembly: February 11, 1886 | Carl Johan Malmsten | April 9, 1814

English clergyman and mathematician | Christ Church | Madeley: April 9, 1813 - Wigginton: December 17, 1853 | Robert Richard Anstice | Madeley: April 9, 1813

Finnish philosopher (1801–1852) | Pieksämäki: April 9, 1801 - Helsinki: April 14, 1852 | Axel Adolf Laurell | Pieksämäki: April 9, 1801 - Helsinki: April 14, 1852

Catalan chemist | Sant Feliu de Guíxols: April 9, 1797 - Barcelona: May 25, 1860 | Josep Roura i Estrada | Sant Feliu de Guíxols: April 9, 1797 - Barcelona

Swedish chemist | Royal Order of the Polar Star (1851) | Stockholm City: April 9, 1797 - Netherlands: October 31, 1852 | Nils Wilhelm Almroth | Stockholm City

Bavarian flautist and tinkerer (1794-1881) | Boehm System | Munich: April 9, 1794 - Munich: November 25, 1881 | Theobald Boehm | Munich: April 9, 1794

Hungarian philosopher | Štítnik: April 9, 1793 - Pest: June 7, 1858 | Gusztáv Szontagh (Gusztav Szontagh) | Štítnik: April 9, 1793 - Pest: June 7, 1858

English mathematician and Anglican cleric (1791–1858) | Fellow of the Royal Society (1818) | Richmond School, Sedbergh School, University of Cambridge, Trinity College

German art collector and artist (1787-1859); collection was sold in 1868 | Verzeichniss der von Herrn Johann Gottlob von Quandt hinterlassenen

chemist and inventor of an electrically powered vehicle | Adorp: April 9, 1785 - Adorp: February 15, 1841 | Sibrandus Stratingh | Adorp: April 9, 1785 - Adorp

Baltic German physicist (1770-1831) | Grand prix des sciences mathématiques (1816) | University of Göttingen, Gustav Adolf Grammar School | Tallinn: April 9

physician and university teacher (1701-1769) | University of Erfurt, Leipzig University, Martin Luther University Halle-Wittenberg | Erfurt: April 9, 1701

Italian philosopher | Vicenza: April 9, 1550 - Valence: January 10, 1635 | Giulio Pace | Vicenza: April 9, 1550 - Valence: January 10, 1635

German astrologer and historical writer | University of Tübingen | Bietigheim-Bissingen: April 9, 1499 - Magdeburg: February 22, 1537 | Johann Carion